It is not sufficient to say that great ef fects are produced in blasting rock with sand tamping: the question is, would they not be greater with different tamping?

By increasing the quantity of the powder, great effects may be produced without any tamping at all, merely by the resistance of the atmosphere.

An hundred weight of gunpowder placed in mass on the crown of an ordinary arch, and fired, without any loading over it whatever, will break through and destroy the arch. Gates of cities

have been frequently blown in by suspending about the same quantity in bags against them and exploding it, as was done at Ghuznee.

Thus when rocks are blasted with sand tamping, the effects may be considerable, and yet not so great as they might be.

It is the more easy to be deceived on this point, as the results of my experience, and of many experiments, tend to show that usually much more powder is used in blasting rock than is necessary, and I should be glad to know by what rule Mr. Wilson is in the habit of apportioning his charges of powder.

Of the superiority of igniting charges by galvanism, as an ordinary mode, I am very far from being convinced.

I can quite understand its advantage under some circumstances; but I take it they would be few in comparison, and that the use of galvanism should be considered the exception, and not the rule.

Mr. Wilson is quite wrong in the statement, that the fuse is inapplicable under water; I speak of Beckford's patent fuse. There is a kind prepared expressly for using under water. I have tried it many times, and exploded powder with it, at from 25 to 40 feet under water, the fuse being lighted from the top, and it never failed. I know of rock being blasted with it to great advantage in from 20 to 30 feet water, by means of a diving-bell, to clear a foundation for a wharf wall. The holes were bored from the bell, and loaded each by a waterproof cartridge, to which five or six feet of the proper kind of fuse was attached; this was lighted in the bell, and the burning end immediately passed under the edge of the bell to the outside, to prevent the annoyance of the vapour to the workmen. The bell was then, according to signal, raised a short distance, and re

moved a little to one side till after the explosion, when it was lowered again to the spot for the removal of the broken rock, &c.

The operation was in this manner carried on rapidly, and I doubt whether any application of the galvanic battery could have been so advantageous.

I would strongly recommend no one to be deterred from the use of the fuse, until he has tried it well himself; the cost of trial will be small; the common kind is sold, I believe, at about one halfpenny per running foot; that prepared for water-work, called sump fuse, at a little more. The galvanic battery may

be substituted afterwards, if it is considered desirable.

Sir, your obedient servant,

J. F. B.

THE PATENT "BOCCIUS LIGHT."

66

The passing remark which we made on this luminary" of the day, among the "Notes and Notices" in our 996th Number, has led to so many applications to us for further information on the subject from our country friends more especially-and to so much complaint, also, of unmerited disparagement, on the part of the patentee and his friends, that respect for the reasonable curiosity of the former, if not for the matter-of-course chagrin of the latter, and a regard for our own reputation as honest and impartial journalists, combine to make it indispensable that we should explain more at large our reasons for the opinion we have expressed.

We shall first do the inventor-if so he can be called-the justice of laying before our readers a Report which has been made to him, on the properties of his light, by Professor Brande and Mr. Josiah Parkes, with a copy of which he has himself been good enough to favour us, and which he seems to look upon as so overwhelming an affair, that it leaves not a word more to be said!

Report on Mr. Boccius's Patent Gas Burners; by William Thomas Brande, Esq., Professor of Chemistry, and Josiah Parkes, Esq., Civil Engineer.

TO GOTTLIEB BOCCIUS, ESQ. Sir,-Having requested us to make a series of experiments on your newly Patented Gas Burner, and to report to you

our opinion of its merits as compared with the burners in ordinary use: desiring also that we should pursue such methods of investigation as might seem to us most advisable for ascertaining the quality of the light produced, its illuminating power, and the general fitness of your invention for practical purposes, we have to report as follows:

1st. We selected as the standard of comparison between your burners and those in common use, the ordinary Argand burner, consuming five cubic feet of gas per hour, and having a flame of from 2 inches to 24 inches in height above the jet holes.

2nd. The measurement of the quantities of gas consumed in a given time by the different burners submitted to experiment was determined by a gasometer, not by a gas

meter; the former being considered less liable to accidental error, and to give more precise results than the latter.

3rd. With respect to the means adopted for ascertaining the relative intensities, or illuminating powers, of the several lights, we used both the method of shadows, and Professor Wheatstone's new photometer, which gave results in remarkable accordance with each other; the average results of the two methods, on numerous and frequently repeated experiments, not differing more than 24 per cent. Precautions were taken for

measuring the respective distances of the lights from the instruments with strict accuracy.

The burners with which you furnished us for experiment were of the following diameters, viz. :—

The light afforded by each of these burners is of a decidedly whiter, more brilliant, and more agreeable character, than that of the ordinary Argands; qualities which appear to arise from the more perfect combustion obtained by the arrangement of the apparatus of your burner.

The illuminating power of the light derived from an equal quantity of gas, was found, in your single burners, to be from 45 to 50 per cent. greater than the light given by the common Argand. In the double and treble ring burners, above specified, the economy amounted to at least 60 per cent.; and some experiments between your burners and the batswing, gave a still higher ratio in favour of your light.

Of the fitness of your burners for the general purposes of illumination there can be no doubt. Their construction is so simple, that no additional trouble or skill is required for their management; and as, with a smaller consumption of gas, they afford a larger quantity of light, the deleterious products of combustion must, in them, be relatively less than in burners of the ordinary kind. We are also of opinion that your burners are well adapted for the application of a simple and effective mode of ventilation, attainable by lengthening the central chimney, and, by its means, conveying away the heat of the flame, and the products of combustion.

We cannot conclude this Report without expressing our conviction that your invention is calculated to produce a valuable improvement in the art of illumination by gas, as well as to promote its more universal adoption for domestic purposes; inasmuch as the economy effected by your burners is not

larger or outer ring.

confined to the use of any particular size of light, but extends to all lights, whether adapted to the demands of a small apartment, or to the illumination of the largest halls, public places, buildings and streets. We remain, Sir,

Your obedient servants,
WM. THOS. BRANDE,
JOSIAH PARKES.

London, August 2nd, 1842.

The first remarkable thing in this Report, which we have to notice, is, that the learned Reporters nowhere assign any sufficient reason for the superiority which they are pleased to assign to the

66

Boccius," over all preceding lights. It is stated to be "a valuable improvement in the art of illumination by gas," and something is said also about " more perfect combustion;" but in what "the valuable improvement" consists, and how the "more perfect combustion" is effected, the reader is left to find out for himself. If there were really any novelty in the construction of the Boccius lamp of a nature likely to render it preferable to others, why not tell us at once all about it?

Another remarkable thing is, that Messrs. Brande and Parkes should have thought of selecting, as "a standard of comparison," by which to test the value of the "Boccius Light," and the degree in which it is an improvement—a step in advance "in the art of illumination by gas "-the common Argand burner.' This is just as if the inventor of the last improved steam-engine were to ask us

to judge of its worth by comparing it with the rude atmospheric engine of a century ago. Why not select for the standard of comparison the last best light invented previous to the appearance of the "Boccius? Why not take up the course of improvement where Mr. Boccius found it, and show what the advances really are which he is supposed to have made? So far as the truth of the case is concerned, the very learned and most impartial Reporters might as well have chosen for their standard of comparison, the oil lamps of the last generation, or the still older horn lamps of the days of King Alfred.

The reason for this selection of the common Argand burner for the standard of comparison, becomes abundantly manifest when we look to the results which the reporters obtained by it. "The illuminating power," they say, "of the light derived from an equal quantity of gas was found in your single burners to be from 45 to 50 per cent. greater than the light given by the common Argand; on the double and treble ring burners the economy amounted to at least 60 per cent.; and some experiments between your burners and the batswing gave a still higher ratio in favour of your light." Now all this might very well be, and yet the Boccius Light have nothing at all to boast of, over other lights well known to the public long before it was ever heard of. Dr. Ure, for example, says of the Bude Light, "It gives as much light as the best Argand gas flames with only half the expenditure of gas. A common Argand gas flame was found to emit a light equal to ten wax candles (8 to the lb.), and a Bude burner, called No. 10, gave a light equal to 94.7 of the candles. Thus, the Bude flame had nearly ten times the illuminating power of the gas Argand flame; while, by means of an accurate gas meter, the former was ascertained to consume only 4:4 times the quantity of gas consumed by the latter, demonstrating the economy of the Bude Light over common gas to be GREATER than two to one, and this economy increases in proportion to the magnitude of the light." The results which Messrs. Brande and Parkes obtained from a comparison of the Boccius Light, with the common Argand burner, differ therefore in no respect from those which had been before realized by means of the Bude

Light; and had they selected for their standard of comparison-as they ought in all fairness to have done-the Bude Light, by which the common Argand had already been so greatly eclipsed, they must have been compelled to report-special instructions and handsome retainers notwithstanding-that the Boccius Light, so far from being "a valuable improvement in the art of illumination by gas," has not advanced the art a single step.

Nor is it any wonder this should be the case; for if we pass from the Report of Messrs. Brande and Parkes, in which very prudently nothing is said as to the construction of the Boccius lamp, to the specification of the patentee himself, (see Mech. Mag., No. 994, p. 212,) where of necessity he was obliged to explain in what his supposed improvements in combustion consist, we shall find that the means he employs (so far as the production of flame is concerned) are precisely the same as those employed by Mr. Gurney. Like causes could of course only produce like effects. Mr. Boccius supplies the gas to the burner through the medium of three concentric rings, freely exposed to the atmosphere, pierced at top with a great number of small holes; so also does Mr. Gurney. (See Mech. Mag., No. 981, p. 419.) Mr. Boccius "places the inner ring at a certain height above the outer one, or that next to it;" and he is careful to tell us that this arrangement “he considers to be a great improvement on burners of the same kind heretofore made;" but so also did Mr. Gurney, before Mr. Boccius reproduced this "great improvement"as any person may satisfy himself who will be at the trouble to pay a visit to the shop of Messrs. Hitchcock and Rogers, St. Paul's Churchyard, which was fitted up during the last winter with Bude Lights, and where the construction of them can be inspected with great facility.

The only real difference between the two lamps consists in the chimneys; for whereas Mr. Gurney employs two chimneys, one rising a short way within the other, but both placed at a little distance from the flame, Mr. Boccius makes use of "two or more concentric chimneys, or cylinders, in addition to and within the usual chimney of glass," the innermost of which chimneys is in actual contact with the flame, and which it is

therefore necessary to make of "thin sheet iron," or some other substance "capable of withstanding the heat." How any advantage can be gained from this multiplication of chimneys, or from the dipping of the innermost into the flame, neither Mr. Boccius nor his learned auxiliaries, Messrs. Brande and Parkes, have been pleased to explain, and we are ourselves utterly at a loss to divine. We are warranted by their own experiments in saying that there is in reality no advantage whatever; since it stands confessed that no more light is obtained from the Boccius lamp, with its additional chimneys, than was before obtained by the Gurney lamp without them. All the effect which the innermost chimney of "thin sheet iron," even when heated to the utmost, has, is to cast a dark shadow over the light; and, so far as this may be considered an advantage, Mr. Boccius must be allowed to have outstripped all competition.

We must guard our readers against assuming that, because we oppose to the Boccius Light the merits of the Bude, we have any desire to set up the personal rights or claims of Mr. Gurney against those of Mr. Boccius. We stated sometime ago (No. 981, p. 419) our reasons for being of opinion that Mr. Gurney is identified with the Bude Light more by false pretension than by original invention; and we desire to be understood as not departing from that opinion in the least. In speaking of him on the present occasion as the actual inventor, we have done so for convenience sake merely, waving altogether for the moment the question of historical truth. As far as Mr. Boccius is concerned, it matters not one jot how the question as to the invention of the Bude Light stands,—whether the credit of it belongs wholly to Mr. Gurney, or whether he only embodied the floating ideas and suggestions of others. Be that as it may, this at least is certain, that it was a thing done, un fait accompli, and a thing too of the greatest possible notoriety, at the date of Mr. Boccius' appear ance on the scene. It is evidence decisive and unimpeachable of what the state of the art of gas illumination was at that date, and furnishes an infallible test by which to judge how far Mr. Boccius has carried us beyond it. Now we have seen that before the Boccius era, the common Argand lamp had been improved upon to

the extent of more than 50 per cent.; and we have seen also that Messrs. Brande and Parkes claim for the Boccius Light a superiority over the same common Argand lamp of but from 45 to 60 per cent. The gain by the Boccius Light, therefore, is literally and truly NOTHING. The art of gas illumination remains just where it was before Mr. Boccius conceived the entertaining notion of giving it a lift by reinventing all that he found most approved in the existing practice, and stamping his own outlandish name on all that he could,-under favour of that vigilant guardian of the public rights, the Clerk of the Patents,-abstract from the public common.

Sir, I am sorry that your correspondent, "B.," (p. 282,) should have perused with so little care my communication in your 996th Number. Had he given that paper a little more consideration, I think he would have seen that in reality we differ but little in opinion, and not much in degree.

From this correspondence of opinion I must, however, except the assertion with which "B." commences his angry epistle -that " upon one point all are agreed, viz., that the water at present supplied in London is at once nauseous and noxious-that it is destructive to health, and often to life." To this mis-statement I give an unqualified denial.

That the water as at present supplied (by some of the Companies, especially) is susceptible of great improvement I not only admit, but I assert it; and I also uncompromisingly maintain the great desirableness of that improvement being carried to the utmost possible extent. I have not the pleasure of being acquainted with Mr. Stuckey's plan of filtration; but, from the statements put forth respecting it, I am quite ready to take for granted that it will effectually filter the required quantity of water, with sufficient rapidity, and at a trifling expense, and also be unattended with any of the deteriorating effects which many filters exercise upon the fluid passing through them. Further, I am also prepared to admit, that it would be beneficial if the several Water Companies could be induced, or

even compelled to adopt so excellent an invention.

The fact, however, is, that there are Two sources of impurity in our water supply, of unequal magnitudes; and I hold, with your correspondent "B.," that it is "highly mischievous to fix the public attention wholly upon one source of impurity, and that possibly the smallest, to the exclusion of all consideration for the other, which may turn out to be the greatest.

Now, in my former letter I stated that nine-tenths of the impurities to be found in our cisterns enter the water after it has been received from the Water Company. That is to say, that the quantity of impurities contained in, and supplied with the water seldom amounts to, and never exceeds, one-tenth of the whole. To this original and really minute quantity, continual additions are being made by the action of the wind, rain, &c., and the contents of the cistern become charged with blacks, dust, moths, flies, spiders, caterpillars, &c., with other animal and vegetable substances, according to the situation of the cistern.

Your correspondent, "B.," speaks of "an ascertained and proved remedy, which would prevent any dirt from entering into our cistrens at all!" Now, this is the grand desideratum, and if such a remedy has indeed been found, I shall rejoice to become acquainted with it; but I confess that in this matter "the eye of faith is dim."

What I wish to impress on your readers is this, that merely delivering a supply of pure water into our cisterns, as at present regulated, will be literally casting pearls before swine. "B." says, my present remedy "is good as far as it goes." I consider it undeserving of the name of "remedy." I merely suggest it as a precaution-a precaution necessary at all times, whatever improvements may hereafter take place in the supply. A precaution which, as far as it goes, will positively prevent any "destruction of health," or "loss of life," and therefore one that the public should well understand to be at their own command. It is a precaution, moreover, which, if still unattended to, must render nugatory all the care and expense that may be incurred to supply pure water. Our cisterns must be so closed as to exclude all those deteriorating substances which now

so freely enter, and the whole mass of water must be frequently changed. A body of even "beautifully-filtered water," allowed to become stagnant, will be as noxious and unwholesome as any portion of that now supplied.

In consequence of the public attention being so frequently directed to what I maintain to be the lesser source of evil, I felt it necessary to call their attention to the greater also. To point out the duality of the mischief, and to show the twofold character of the remedy, was the object of my former paper. What I want is, to place the public in a position to second and give effect to any efforts which may be made, either voluntary or compulsory, to increase the purity of the supply.

The "levity," and "sneer at the notice on the order book of the House of Commons," rests entirely in the imagination of your testy correspondent "B." I consider the subject too serious for levity, and most unbecomingly subjected to badinage.

With respect to what "influential members of the government, or "noble lords," may have done, said, or promised in this matter, I do not know, neither do I care. No members of the government, however influential, nor any peer, however noble, can alter facts; that parties will be found ready enough to misrepresent them, there can be no doubt.

"B." cannot attach a higher importance than I do to the enquiry which is "promised;" and I will do him the justice to suppose that he desires nothing but the truth. I beg, however, to say that I desire more,-I desire the whole truth!

It is just possible, though barely probable, that the legislature may direct the water companies to increase the purity of their supply; but if they do not also direct the receivers to increase the purity of their stock, of what benefit will be their labours? The purest possible supply, added to an impure stock, will instantly become impure, and only perpetuate our present evils.

"B." parades the usual bugbears of his class, and speaks of "nauseous and noxious water,' -"diseases generated thereby,"-" destruction of health,""English cholera," and "loss of life."

I suppose "the friendly water of the

Thames" is the worst that "B." can